AGC014B

https://gyazo.com/6964219a87b15e25515e43510edb342e

Thoughts.

For example.

If the query were a single query, it would be impossible regardless of the shape of the tree.

Impossible unless the two queries overlap completely.

If the query is 3 queries ab, bc, ca, then ok.

In other words, it looks good if it's a cycle.

Multiple pieces are possible.

In other words, count the number of times it appears at the end of the query, and if it's an even number of times, it's OK.

Proof.

Odd edges are always formed around the points that the query touches only an odd number of times.

Since it is a tree, the path connecting the two points is unique

When there are ab and bc, the paths that follow abc in this order but not on ac go back and forth twice.

Official Explanation

Policy OK

Proof is considered in mod 2 with rooted trees

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